In many wireless systems, data rates for a given data transfer are assigned to devices based on the signal conditions each device experiences as part of the network. Typically, higher data rates are assigned to devices in good signal conditions, whereas lower data rates are assigned to devices in poor signal conditions. This allows network operators to improve overall system bandwidth because network resources are not wasted on devices that cannot efficiently use them. Different algorithms (i.e., scheduling algorithms) may be used by different systems to optimize the bandwidth.
For example, network resources are usually divided among several physical channels, including both “data” channels used to send traffic/packet data and “control” channels used to send overhead/control data. Channel conditions of received forward link transmissions can be observed by a wireless device (e.g., based on pilot signals) and reported back to a base station. The base station then uses this knowledge to selectively schedule transmissions to the wireless device, including setting the data rate at which transmissions are sent. Different data rates correspond to transmitting data in formats that carry more information bits (i.e., at a higher data rate) or in formats that carry less information bits (i.e., at a lower data rate). That is, if the signal conditions are poor, data can be transmitted in a transmission format with additional redundancies so that corrupted symbols are more likely to be recoverable. Hence, the data rate is lower than if a transmission format without these redundancies were used instead.
Because higher data rates provide more data throughput, higher data rates also require heightened data processing capabilities from both the receiving and transmitting devices. However, when a device configured to process data at a high data rate experiences poor signal conditions and is forced to operate under a reduced data rate, those enhanced processing capabilities are wasted on the lower data rate processing. For example, a 1 GHz processor with a corresponding operating voltage of 1.2V may be needed to process communications at the Evolution-Data Optimized (EV-DO) RevA forward link theoretical maximum data rate of 3.1 Mb/s, but would be an unnecessary drain on energy resources for communications at a lower data rate of 78.6 Kb/s. Heretofore, system designers have neglected the effects of changing data rates on energy consumption (e.g., battery life) when setting the processing parameters of a wireless device.